The invention relates to glass containers which can be sterilized for medical purposes, in particular for the storage of pharmaceutical or diagnostic products, including solutions. Such containers are intended to come into direct contact with their contents. A varied selection of glass containers are used, for example, small bottles (described in detail in, for example, the ISO norm 8362, section 1), ampoules (described in detail in, for example, the ISO norm 9187, section 1), syringe bodies (described in detail in, for example, the ISO norm 11040, section 4), glass cylinders (described in detail in, for example, the ISO norm 13926, section 1), as well as bottles (described in detail in, for example, the ISO norm 8356, section 1). The filling volume of these types of containers varies from 0.5 to 2000 ml.
For these purposes, for example, for the packaging of injection solutions, glasses with a high hydraulic resistance are necessary (in accordance with the pharmacopoeia, for example, the German Pharmacopoeia DAB 10, glass of the type I or II). Examples of glass containers which fulfill this demand are disclosed in the German utility model DE 296 09 958.U1 which describes glass containers whose surfaces are in contact with the solutions and are have a coating of oxides and/or nitrides of the elements Si, Ti, Ta, Al by way of a plasma chemical vapor deposition (CVD) procedure.
For a vast number of medical and pharmaceutical uses, it is necessary to sterilize the empty containers before filling them. Sterilization methods suitable for glass containers at the moment involve costly technical chemical procedures such as fumigation with ethylene oxide, autoclaving with overheated water vapor and heat sterilization at temperatures of between 250 and 300.degree. C. There is a great need for the improvement of these containers and in their associated methods of use.
Further methods of sterilization using high energy radiation (for example .beta.-radiation, .gamma.-radiation and strong UV-radiation) are not suitable in this case since current glasses, for example, common borosilicate glasses or soda-lime silica glasses, will discolor heterogeneously yellow to brown, often in a spotty manner after the sterilization due to the high energy radiation, depending on the radiation dose. Such discoloration varies depending on time, temperature and the influence of light. Accordingly, it is frequently impossible to render a dependable visual inspection of the contents.
The examination of, for example, a powdery content, for foreign particles would not be dependable in a heterogeneously (spotty) discolored container. Given the high degree of automation in production lines today, any noticeable deviation from a pre-determined norm would lead to a sorting out of the container in question and could possibly even lead to a halt of an entire production line.
The use of high energy radiation for sterilization can also be advantageous for previously filled containers. In this case, also, a discoloration of the container is unacceptable since it would gravely limit the ability of the pharmaceutical producer, the pharmacist, and the user to monitor or control the content. For the consumer, it is important that, for example, two containers which contain the same product are visually identical since otherwise it would be very difficult to clearly identify the container which may contain a spoiled product.
The addition of stabilizers, in particular, cerium (Ce), has long been known in glass chemistry to suppress the brown discoloration caused by high energy radiation. However, cerium containing glasses have not been suitable for use as containers for storage of pharmaceutical and diagnostic solution since Ce-ions could be released into the solution during storage and other glass components, such as SiO.sub.2, AI.sub.2 O.sub.3, etc., are released after the radiation to a greater extent than in non-irradiated containers. The interaction of the content with the diffused Ce-ions could be critical or, in other words, could gravely influence the effectiveness of the medicine. Accordingly, the contents of every container would have to be examined under varying storage conditions and times. This would entail immense testing expenditure.